Magnetic memory with porous non-conductive current confinement layer

ABSTRACT

A magnetic element having a ferromagnetic pinned layer, a ferromagnetic free layer, a non-magnetic spacer layer therebetween, and a porous non-electrically conducting current confinement layer between the free layer and the pinned layer. The current confinement layer forms an interface either between the free layer and the non-magnetic spacer layer or the pinned layer and the non-magnetic spacer layer.

BACKGROUND

Spin torque transfer technology, also referred to as spin electronics,which is based on changing magnetic state of the system by momentumtransfer from conduction electrons, is a recent development. Spin torqueRAM or ST RAM is a non-volatile random access memory application thatutilizes spin torque technology. Digital information or data,represented as a “0” or “1”, is storable in the alignment of magneticmoments within a magnetic element. The resistance of the magneticelement depends on the moment's alignment or orientation. The storedstate is read from the element by detecting the component's resistivestate.

The magnetic element, in general, includes a ferromagnetic pinned layer(PL), and a ferromagnetic free layer (FL), each having a magnetizationorientation. The magnetic element also includes a non-magnetic barrierlayer. The respective magnetization orientations of the free layer andthe pinned layer define the resistance of the overall magnetic element.When the magnetization orientations of the free layer and pinned layerare parallel, the resistance of the element is low (R_(L)). When themagnetization orientations of the free layer and the pinned layer areantiparallel, the resistance of the element is high (R_(H)). Themagnetization orientation is switched by passing a currentperpendicularly through the layers. The current direction is differentfor writing “1” or ‘0”. To write “1” (R_(H)) the current flows from thepinned layer to the free layer, and reversed to flow from the free layerto the pinned layer to write “0” (R_(L)).

It is desirous to reduce the switching current needed to switch the freelayer magnetization orientation, since larger chip capacity and/orreduced power consumption is achieved.

BRIEF SUMMARY

This present disclosure is directed to magnetic elements, such astunneling magnetoresistive elements, that include a current confinementlayer. The magnetic elements have a plurality of layers including aporous non-conductive current confinement layer. Utilizing such acurrent confinement layer increases the current density within thecurrent path in the free layer of the element, thus reducing theswitching current of the element.

In one particular embodiment, this disclosure provides a magneticelement having a ferromagnetic pinned layer, a ferromagnetic free layer,a non-magnetic spacer layer therebetween, and a porous non-electricallyconducting current confinement layer between the free layer and thepinned layer. The current confinement layer may be between the freelayer and the non-magnetic spacer layer, providing an interface betweenthe free layer and the non-magnetic spacer layer, or the currentconfinement layer may be between the pinned layer and the non-magneticspacer layer, providing an interface between the pinned layer and thenon-magnetic spacer layer.

These and various other features and advantages will be apparent from areading of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be more completely understood in consideration of thefollowing detailed description of various embodiments of the disclosurein connection with the accompanying drawings, in which:

FIG. 1A is a cross-sectional schematic diagram of an illustrativemagnetic element with in-plane magnetization orientation in a lowresistance state; FIG. 1B is a cross-sectional schematic diagram of themagnetic element in a high resistance state;

FIG. 2 is a cross-section schematic diagram of an illustrative magneticelement with out-of-plane magnetization orientation;

FIG. 3 is a cross-sectional schematic diagram of a first embodiment of amagnetic element having a current confinement layer; FIG. 3A is anenlarged view of a portion of the magnetic element of FIG. 3;

FIG. 4 is a cross-sectional schematic diagram of a second embodiment ofa magnetic element having a current confinement layer;

FIG. 5 is a cross-sectional schematic diagram of a third embodiment of amagnetic element having a current confinement layer; FIG. 5A is anenlarged view of a portion of the magnetic element of FIG. 5;

FIG. 6 is a cross-sectional schematic diagram of a fourth embodiment ofa magnetic element having a current confinement layer;

FIG. 7 is a schematic top view of a porous layer suitable for use as acurrent confinement layer;

FIG. 8 is a schematic top view of a second embodiment of a porous layersuitable for use as a current confinement layer; FIG. 8A is a schematicside view of the porous layer of FIG. 8 incorporated into anillustrative magnetic element; and

FIG. 9A is a flow diagram of a method of making a magnetic elementhaving a current confinement layer; and FIG. 9B is a flow diagram of amethod of making a magnetic element having a current confinement layer.

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanying setof drawings that form a part hereof and in which are shown by way ofillustration several specific embodiments. It is to be understood thatother embodiments are contemplated and may be made without departingfrom the scope or spirit of the present disclosure. The followingdetailed description, therefore, is not to be taken in a limiting sense.The definitions provided herein are to facilitate understanding ofcertain terms used frequently herein and are not meant to limit thescope of the present disclosure.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” encompass embodiments having pluralreferents, unless the content clearly dictates otherwise. As used inthis specification and the appended claims, the term “or” is generallyemployed in its sense including “and/or” unless the content clearlydictates otherwise.

The present disclosure relates to magnetic elements having a currentconfinement layer within the stack. The construction can be used forboth in-plane magnetic elements where the magnetization orientation ofthe magnetic layer is in the stack film plane and out-of-plane magneticelements where the magnetization orientation of the magnetic layer isout of the stack film plane, e.g., perpendicular to the stack plane. Thecurrent confinement layer is a porous non-conductive layer presentbetween the pinned layer and the free layer, either between thenon-magnetic spacer layer and the free layer or between the non-magneticspacer layer and the pinned layer. While the present disclosure is notso limited, an appreciation of various aspects of the disclosure will begained through a discussion of the examples provided below.

FIGS. 1A and 1B are cross-sectional schematic diagrams of anillustrative magnetic element 10; in FIG. 1A, element 10 is in the lowresistance state, with the magnetization orientations parallel and inFIG. 1B, element 10 is in the high resistance state, with themagnetization orientations anti-parallel. Magnetic element 10 may alsobe referred to as a variable resistive memory cell or variableresistance memory cell or the like.

Magnetic element 10 includes a ferromagnetic free layer 12 and aferromagnetic reference (i.e., pinned) layer 14. Ferromagnetic freelayer 12 and ferromagnetic pinned layer 14 are separated by anon-magnetic spacer layer 13. Proximate ferromagnetic pinned layer 14 isan antiferromagnetic (AFM) pinning layer 15, which pins themagnetization orientation of ferromagnetic pinned layer 14 by exchangebias with the antiferromagnetically ordered material of pinning layer15. Examples of suitable pinning materials include PtMn, IrMn, andothers. Note that other layers, such as seed or capping layers, are notdepicted for clarity. The interface between free layer 12 andnon-magnetic spacer layer 13 is identified as interface 19.

Ferromagnetic layers 12, 14 may be made of any useful ferromagnetic (FM)material such as, for example, Fe, Co or Ni and alloys thereof, such asNiFe and CoFe, and ternary alloys, such as CoFeB. Either or both of freelayer 12 and pinned layer 14 may be either a single layer or a syntheticantiferromagnetic (SAF) coupled structure, i.e., two ferromagneticsublayers separated by a metallic spacer, such as Ru or Cr, with themagnetization orientations of the sublayers in opposite directions toprovide a net magnetization. Free layer 12 may be a syntheticferromagnetic coupled structure, i.e., two ferromagnetic sublayersseparated by a metallic spacer, such as Ru or Ta, with the magnetizationorientations of the sublayers in parallel directions. Either or bothlayer 12, 14 are often about 0.1-10 nm thick, depending on the materialand the desired resistance and switchability of free layer 12.

If magnetic element 10 is a magnetic tunnel junction cell, non-magneticspacer layer 13 is an insulating barrier layer sufficiently thin toallow tunneling of charge carriers between pinned layer 14 and freelayer 12. Examples of suitable electrically insulating material includeoxides material (e.g., Al₂O₃, TiO_(x) or MgO). If magnetic element 10 isa spin-valve cell, non-magnetic spacer layer 13 is a conductivenon-magnetic spacer layer. For either a magnetic tunnel junction cell ora spin-valve, non-magnetic spacer layer 13 could optionally be patternedwith free layer 12 or with pinned layer 14, depending on processfeasibility and device reliability.

The following are various specific examples of magnetic tunnel junctioncells. In some embodiments of magnetic element 10, layer 13 is oxidebarrier Ta₂O₅ (for example, at a thickness of about 0.5 to 1 nanometer)and ferromagnetic free layer 12 and ferromagnetic pinned layer 14include NiFe, CoFe, or Co. In other embodiments of magnetic tunneljunction cells, layer 13 is GaAs (for example, at a thickness of about 5to 15 nanometers) and ferromagnetic free layer 12 and ferromagneticpinned layer 14 include Fe. In yet other embodiments of magnetic tunneljunction cells, layer 13 includes Al₂O₃ (for example, a few nanometersthick) and ferromagnetic free layer 12 and ferromagnetic pinned layer 14include NiFe, CoFe, or Co. In yet other embodiments of magnetic tunneljunction cells, layer 13 includes crystalline MgO layer (e.g., about 1nm thick) and ferromagnetic free layer 12 and ferromagnetic pinned layer14 include Fe, CoFeB, NiFe, CoFe, or Co. The dimensions of magneticelement 10 are small, from about 10 to about a few hundred nanometers.

Returning to FIGS. 1A and 1B, a first electrode 16 is in electricalcontact with ferromagnetic free layer 12 and a second electrode 17 is inelectrical contact with ferromagnetic pinned layer 14 via pinning layer15. Electrodes 16, 17 electrically connect ferromagnetic layers 12, 14to a control circuit providing read and write currents through layers12, 14. The resistance across magnetic element 10 is determined by therelative orientation of the magnetization vectors or magnetizationorientations of ferromagnetic layers 12, 14. The magnetization directionof ferromagnetic pinned layer 14 is pinned in a predetermined directionby pinning layer 15 while the magnetization direction of ferromagneticfree layer 12 is free to rotate under the influence of spin torque.

FIG. 1A illustrates magnetic element 10 where the magnetizationorientation of ferromagnetic free layer 12 is parallel and in the samedirection of the magnetization orientation of ferromagnetic pinned layer14. FIG. 1B illustrates magnetic element 10 where the magnetizationorientation of ferromagnetic free layer 12 is anti-parallel and in theopposite direction of the magnetization orientation of ferromagneticpinned layer 14.

Switching the resistance state and hence the data state of magneticelement 10 via spin-transfer occurs when a current, under the influenceof a magnetic layer of magnetic element 10, becomes spin polarized andimparts a spin torque on free layer 12 of magnetic element 10. When asufficient level of polarized current and therefore spin torque isapplied to free layer 12, the magnetization orientation of free layer 12can be changed among different directions and accordingly, magneticelement 10 can be switched between the parallel state (i.e., as in FIG.1A), the anti-parallel state (i.e., as in FIG. 1B), and other states.

Similar to magnetic tunnel junction cell 10 of FIG. 1, magnetic tunneljunction cell 20 of FIG. 2 has relatively soft ferromagnetic free layer22 and a ferromagnetic reference (i.e., fixed or pinned) layer 24separated by a non-magnetic layer 23. Pinned layer 24 can be a singlelayer with large coercivity or a layer pinned by a pinning layer, or asynthetic antiferromagnetic (SAF) trilayer, or a SAF pinned by a pinninglayer (not illustrated). The interface between free layer 22 andnon-magnetic spacer layer 23 is identified as interface 29. A firstelectrode 26 is in electrical contact with ferromagnetic free layer 22and a second electrode 27 is in electrical contact with ferromagneticpinned layer 24. Other layers, such as seed or capping layers, are notdepicted for clarity. Electrodes 26, 27 electrically connectferromagnetic layers 22, 24 to a control circuit providing read andwrite currents through layers 22, 24. The various elements of cell 20are similar to the element of cell 10, described above, except that themagnetization orientations of layers 22, 24 are oriented perpendicularto the layer extension rather than in the layer plane.

Free layer 22 and pinned layer 24 each have a magnetization orientationassociated therewith, illustrated in FIG. 2, where two opposingmagnetization arrows represent a readily switchable magnetizationorientation. In some embodiments, magnetic tunnel junction cell 20 is inthe low resistance state or “0” data state where the magnetizationorientation of free layer 22 is in the same direction of themagnetization orientation of pinned layer 24. In other embodiments,magnetic tunnel junction cell 20 is in the high resistance state or “1”data state where the magnetization orientation of free layer 22 is inthe opposite direction of the magnetization orientation of pinned layer24. In FIG. 2, the magnetization orientation of free layer 22 isundefined.

Similar to cell 10 of FIG. 1, switching the resistance state and hencethe data state of magnetic tunnel junction cell 20 via spin-transferoccurs when a current, passing through a magnetic layer of magnetictunnel junction cell 20, becomes spin polarized and imparts a spintorque on free layer 22. When a sufficient spin torque is applied tofree layer 22, the magnetization orientation of free layer 22 can beswitched between two opposite directions and accordingly, magnetictunnel junction cell 20 can be switched between the low resistance stateor “0” data state and the high resistance state or “1” data state.

The illustrative spin-transfer torque magnetic elements 10, 20 are usedto construct a memory device where a data bit is stored in the spintorque memory cell by changing the relative magnetization state of freelayer 12, 22 with respect to pinned layer 14, 24. The stored data bitcan be read out by measuring the resistance of element 10, 20 whichchanges with the magnetization direction of free layer 12, 22 relativeto pinned layer 14, 24.

In order for the spin-transfer torque magnetic element 10, 20 to havethe characteristics of a non-volatile random access memory, free layer12, 22 exhibits thermal stability against random fluctuations so thatthe orientation of free layer 12, 22 is changed only when it iscontrolled to make such a change. This thermal stability can be achievedvia the magnetic anisotropy using different methods, e.g., varying thebit size, shape, and crystalline anisotropy. Additional anisotropy canbe obtained through magnetic coupling to other magnetic layers eitherthrough exchange or magnetic fields. Generally, the anisotropy causes asoft and hard axis to form in thin magnetic layers. The hard and softaxes are defined by the magnitude of the external energy, usually in theform of a magnetic field, needed to fully rotate (saturate) thedirection of the magnetization in that direction, with the hard axisrequiring a higher saturation magnetic field.

In accordance with this disclosure, the magnetic elements include acurrent confinement layer present between free layer 12, 22 and pinnedlayer 14, 24, either between free layer 12, 22 and non-magnetic spacerlayer 13, 23 or between pinned layer 14, 24 and non-magnetic spacerlayer 13, 23. Including a current confinement layer decreases theswitching current needed to switch the magnetization orientation of freelayer 12, 22. FIGS. 3 through 6 illustrates a magnetic element having acurrent confinement layer present between the free layer and the pinnedlayer; FIGS. 3 and 4 illustrate embodiments having a current confinementlayer between the free layer and the non-magnetic spacer layer and FIGS.5 and 6 illustrate embodiments having a current confinement layerbetween the non-magnetic spacer layer and the pinned layer.

Similar to magnetic element 10 discussed above, magnetic element 30 ofFIG. 3 has a ferromagnetic free layer 32 and a ferromagnetic reference(i.e., pinned) layer 34 separated by a non-magnetic spacer layer 33.Proximate ferromagnetic pinned layer 34 is an antiferromagnetic (AFM)pinning layer 35, which pins the magnetization orientation offerromagnetic pinned layer 34 by exchange bias with theantiferromagnetically ordered material of pinning layer 35. Themagnetization orientation of free layer 32 is illustrated as undefinedin FIG. 3. Layers such as seed or capping layers are not depicted forclarity. A first electrode 36 is in electrical contact withferromagnetic free layer 32 and a second electrode 37 is in electricalcontact with ferromagnetic pinned layer 34 via pinning layer 35.

Magnetic element 30 includes a current confinement layer 38 presentbetween free layer 32 and pinned layer 34. In the illustratedembodiment, current confinement layer 38 is positioned between freelayer 32 and non-magnetic spacer layer 33; in some embodiments, thereare no intervening layers between free layer 32 and current confinementlayer 38 and between non-magnetic spacer layer 33 and currentconfinement layer 38, but rather, current confinement layer 38 has aninterface with free layer 32 and with non-magnetic spacer layer 33,respectively. Current confinement layer 38 has a first interface 39Awith free layer 32 and a second interface 39B with non-magnetic spacerlayer 33.

Similar to magnetic element 20 discussed above, magnetic element 40 ofFIG. 4 has a ferromagnetic free layer 42 and a ferromagnetic reference(i.e., pinned) layer 44 separated by a non-magnetic spacer layer 43. Themagnetization orientation of free layer 42 is illustrated as undefinedin FIG. 4. Layers such as seed or capping layers are not depicted forclarity. In some embodiments, however, an in-plane soft magnetic layer(e.g., CoFeB) may be present to improve the TMR ratio of element 40. Afirst electrode 46 is in electrical contact with ferromagnetic freelayer 42 and a second electrode 47 is in electrical contact withferromagnetic pinned layer 44.

Magnetic element 40 includes a current confinement layer 48 presentbetween free layer 42 and pinned layer 44, particularly positionedbetween free layer 42 and non-magnetic spacer layer 43; in someembodiments, there are no intervening layers between free layer 42 andcurrent confinement layer 48 and between non-magnetic spacer layer 43and current confinement layer 48, but rather, current confinement layer48 has an interface with free layer 42 and with non-magnetic spacerlayer 43, respectively. Current confinement layer 48 has a firstinterface 49A with free layer 42 and a second interface 49B withnon-magnetic spacer layer 43.

Current confinement layer 38, 48 limits the path through which electronsmay pass between non-magnetic spacer layer 33, 43 to free layer 32, 42,thus increasing the current density in the current path. The increasedcurrent density results in an overall lower current needed to switch themagnetization orientation of free layer 32, 42.

Current confinement layer 38, 48 is a porous electrically non-conductingmaterial, such as an insulating or dielectric material. Electrons areable to pass through current confinement layer 38, 48 only in areas voidof non-conducting material. These areas void of non-conducting materialmay have ferromagnetic material (i.e., from free layer 32, 42) ornon-magnetic material (i.e., from non-magnetic spacer layer 33, 43)therein; in most embodiments, the void areas having ferromagneticmaterial therein. The areas void of non-conducting material provide aclean interface between free layer 32, 42 and non-magnetic spacer layer33, 43, identified as interface 39C in FIGS. 3 and 3A and as interface49C in FIG. 4. This clean interface 39C, 49C preserves the TMR ratio(e.g., at about 10% to 500%) and maintains spin tunneling efficiency.

The placement of current confinement layer 38, 48 between free layer 32,42 and non-magnetic spacer layer 33, 43 rather than in a differentlocation between free layer 32, 42 and pinned layer 34, 44 is preferredfor various reasons. The portions of free layer 32, 42 that have mostimpact on switching current are the free layer/barrier interface (see,for example, interface 19 of element 10 of FIG. 1, which is theinterface between free layer 12 and non-magnetic spacer layer 13) andthat portion of the free layer immediately proximate the non-magneticlayer (see, for example, free layer 12 and non-magnetic spacer layer 13of element 10 of FIG. 1). If the current confinement layer is spacedfrom the free layer/barrier interface (e.g., in the middle of the freelayer or otherwise away from the non-magnetic layer) the freelayer/barrier interface and the free layer immediate proximate thenon-magnetic layer experience much less current confinement effect, ascompared to having the current confinement layer adjacent non-magneticspacer layer 33, 43, as according to this disclosure. Additionally,having a current confinement layer in the middle of free layer orotherwise not at the free layer/barrier interface will impact themagnetic coupling of the entire free layer. This will constrain anyoptimization of the free layer as it affects device performance. Stillfurther, having a current confinement layer between free layer 32, 42and non-magnetic spacer layer 33, 43 provides freedom to free layermaterial selection and process optimization.

Similar to magnetic element 10 discussed above, magnetic element 50 ofFIG. 5 has a ferromagnetic free layer 52 and a ferromagnetic reference(i.e., pinned) layer 54 separated by a non-magnetic spacer layer 53.Proximate ferromagnetic pinned layer 54 is an antiferromagnetic (AFM)pinning layer 55, which pins the magnetization orientation offerromagnetic pinned layer 54 by exchange bias with theantiferromagnetically ordered material of pinning layer 55. Themagnetization orientation of free layer 52 is illustrated as undefinedin FIG. 5. Layers such as seed or capping layers are not depicted forclarity. A first electrode 56 is in electrical contact withferromagnetic free layer 52 and a second electrode 57 is in electricalcontact with ferromagnetic pinned layer 54 via pinning layer 55. Unlikemagnetic element 10 of FIGS. 1A and 1B, however, magnetic element 50 isoriented with free layer 52 at the bottom of the illustrated layer stackand pinning layer 55 at the top. This configuration is due to the methodof manufacturing element 50, where free layer 52 is formed first,non-magnetic layer 53 is applied over free layer 52, etc. It should benoted that the designations of “top” and “bottom” are only used forconvenience herein and any stack structure with the discussed relativeordering of layers is within the scope of this invention.

Magnetic element 50 includes a current confinement layer 58 presentbetween non-magnetic layer 53 and pinned layer 54. In some embodiments,there are no intervening layers between pinned layer 54 and currentconfinement layer 58 and between non-magnetic spacer layer 53 andcurrent confinement layer 58, but rather, current confinement layer 58has an interface with non-magnetic spacer layer 53 and with pinned layer54, respectively. Current confinement layer 58 has a first interface 59Awith non-magnetic spacer layer 53 and a second interface 59B with pinnedlayer 54.

Similar to magnetic element 20 discussed above, magnetic element 60 ofFIG. 6 has a ferromagnetic free layer 62 and a ferromagnetic reference(i.e., pinned) layer 64 separated by a non-magnetic spacer layer 63. Themagnetization orientation of free layer 62 is illustrated as undefinedin FIG. 6. Layers such as seed or capping layers are not depicted forclarity. In some embodiments, however, an in-plane soft magnetic layer(e.g., CoFeB) may be present to improve the TMR ratio of element 60. Afirst electrode 66 is in electrical contact with ferromagnetic freelayer 62 and a second electrode 67 is in electrical contact withferromagnetic pinned layer 64. Unlike magnetic element 20 of FIG. 2,however, magnetic element 60 is oriented with free layer 62 at thebottom of the illustrated layer stack and pinned layer 64 at the top.This configuration is due to the method of manufacturing element 60,where free layer 62 is formed first, non-magnetic layer 63 is appliedover free layer 62, etc.

Magnetic element 60 includes a current confinement layer 68 presentbetween non-magnetic spacer layer 63 and pinned layer 64. In someembodiments, there are no intervening layers between pinned layer 64 andcurrent confinement layer 48 and between non-magnetic spacer layer 43and current confinement layer 48, but rather, current confinement layer68 has an interface with non-magnetic spacer layer 63 and with pinnedlayer 64, respectively. Current confinement layer 68 has a firstinterface 69A with non-magnetic spacer layer 63 and a second interface69B with pinned layer 64.

Similar to current confinement layer 38, 48 described above, currentconfinement layer 58, 68 limits the path through which electrons maypass between pinned layer 54, 64 and non-magnetic spacer layer 53, 63,thus increasing the current density in the current path. The increasedcurrent density results in an overall lower current needed to switch themagnetization orientation of free layer 52, 62.

Current confinement layer 58, 68 is a porous electrically non-conductingmaterial, such as an insulating or dielectric material. Electrons areable to pass through current confinement layer 58, 68 only in areas voidof non-conducting material. These areas void of non-conducting materialmay have ferromagnetic material (i.e., from pinned layer 54, 64) ornon-magnetic material (i.e., from non-magnetic spacer layer 53, 63)therein; in most embodiments, the void areas having ferromagneticmaterial therein. The areas void of non-conducting material provide aclean interface between non-magnetic spacer layer 53, 63 and pinnedlayer 54, 64, identified as interface 59C in FIGS. 5 and 5A and asinterface 69C in FIG. 6. This interface 59C, 69C preserves the TMR ratio(e.g., at about 10% to 500%) and maintains spin tunneling efficiency.

The placement of current confinement layer 58, 68 between non-magneticspacer layer 53, 63 and pinned layer 54, 64 has generally the samebenefits as positioning the current confinement layer between thenon-magnetic spacer layer and the free layer (as for elements 30, 40,described above). It is desirable to position current confinement layer58, 68 at the interface between non-magnetic spacer layer 53, 63 andpinned layer 54, 64 rather than in a different location, such as withinthe pinned layer.

An example of a porous layer suitable for use as current confinementlayer 38, 48, 58, 68 is shown in FIG. 7 as apertured material 70.Apertured material 70 has an extension of non-conducting material 72having at least one, but usually a plurality of, apertures 75 extendingthrough material 70. In the illustrated embodiment, apertures 75 arenon-random and precisely spaced within non-conducting material 72; inalternate embodiments, the apertures may be randomly ordered and/or withinconsistent spacing therebetween. For material 70 of FIG. 7, eachaperture 75 has a generally circular shape with a diameter of about2-200 Angstroms. Other apertured materials suitable for use as a currentconfinement layer may have apertures that are oval, square, rectangular,irregular, etc. with a largest dimension of about 2-200 Angstroms, insome embodiments about 5-100 Angstroms, and in some other embodimentsabout 10-30 Angstroms.

Apertures 75 occupy at least about 10% and no more than about 90% of thearea of material 70, leaving at least about 10% and no more than about90% of material 70 being non-conducting material 72. In someembodiments, apertures 75 occupy about 25%-75% of the surface area ofmaterial 70, and in other embodiments, about 40%-60%. The thickness ofapertured layer material 70 may be, for example 2-20 Angstroms, in someembodiments, about 3-5 Angstroms. When apertured material 70 isincorporated into a magnetic element, such as magnetic element 30 ofFIG. 3 or magnetic element 40 of FIG. 4, apertures 75 may be filled byferromagnetic material from free layer 32, 42 or by non-magneticmaterial from non-magnetic spacer layer 33, 43; in most embodiments,apertures 75 have ferromagnetic material therein. Similarly, whenapertured material 70 is incorporated into a magnetic element, such asmagnetic element 50 of FIG. 5 or magnetic element 60 of FIG. 6,apertures 75 may be filled by ferromagnetic material from pinned layer54, 64 or by non-magnetic material from non-magnetic spacer layer 53,63; in most embodiments, apertures 75 have ferromagnetic materialtherein.

Another example of a porous layer suitable for use as currentconfinement layer 38, 48, 58, 68 is shown in FIG. 8 as dotted material80. Dotted material 80 is composed of at least one, but usually aplurality of, discrete regions (e.g., islands, dots, etc.) ofnon-conducting material 82. Surrounding non-conducting material 82 isarea 85 devoid of non-conducting material 82. Non-conducting material 82may have generally any shape, such as circular, oval, square,rectangular, irregular, etc., depending on the mode of forming thediscrete areas of non-conducting material 82. Non-conducting material 82may be domed. Each area of non-conducting material 82 has a largestdimension of about 2-200 Angstroms, in some embodiments about 5-100Angstroms, and in some other embodiments about 10-30 Angstroms.Depending on the mode of forming the discrete areas of non-conductingmaterial 82, the shape and size of non-conducting material 82 may varygreatly. In an alternate embodiment, non-conducting material 82 may beinterconnected, for example, forming a lattice or matrix ofnon-conducting material.

Non-conducting material 82 occupies at least about 10% and no more thanabout 90% of the area of dotted material 80, leaving at least about 10%and no more than about 90% of material 80 being devoid area 85. In someembodiments, non-conducting material 82 occupies about 25%-75% of thesurface area of material 80, and about 40%-60% in other embodiments. Theheight or thickness of non-conducting material 82 may be, for example2-20 Angstroms, in some embodiments, about 3-5 Angstroms.

FIG. 8A illustrates dotted material 80 incorporated into a magneticelement having a ferromagnetic free layer 86, a ferromagnetic pinnedlayer 88 and a non-magnetic spacer layer 87 therebetween. When dottedmaterial 80 is used in the magnetic element of FIG. 8A or any of theother magnetic elements of this disclosure, devoid area 85 is filled byferromagnetic material from free layer 86 or by non-magnetic materialfrom non-magnetic spacer layer 87; in most embodiments, devoid area 85has ferromagnetic material therein.

Apertures 75 or devoid area 85 may extend linearly through porousmaterial 70 or dotted material 80, respectively, directly fromnon-magnetic spacer layer 33, 43 to free layer 38, 48 or fromnon-magnetic spacer layer 53, 63 to pinned layer 54, 64. Alternately,apertures 75 or devoid area 85 may have a tortuous path through porousmaterial 70 or dotted material 80, respectively.

As indicated above, materials 72, 82 are electrically insulating andnon-conductive. In some embodiments, material 72, 82 is a dielectric.Examples of suitable materials for material 72, 82 include alumina(Al₂O₃), zirconia (ZrO₂), silicon dioxide (SiO₂), silicon nitride(Si₃N₄), and composites, such as silicon oxide and carbon (SiO_(x)C).Both apertured material 70 and dotted material 80 may be formed in situ,directly on non-magnetic spacer layer 23 during the formation ofmagnetic element 20.

For example, apertured material 70 may be formed during the forming ofmagnetic element 30, 40, 50, 60 or formed as a layer that issubsequently applied onto non-magnetic spacer layer 33, 43, 53, 63. Forexample, apertured material 70 can be formed by depositing a porousnon-conductive film having pores with diameters of 5-100 Angstroms, orwith diameters of 10-30 Angstroms. An example of such as material ismesoporous silica synthesized with a triblock copolymer. As anotherexample, a porous dielectric or organic film, such as a siliconoxide-carbon composite, can be deposited, with optional subsequentoxidation.

To form an embodiment of dotted material 80, in one example, a thinmetal or metal alloy film can be deposited directly onto non-magneticspacer layer 33, 43, 53, 63 as discontinuous and discrete islands. Theseislands are then oxidized, to create a non-conductive material (e.g.,metal oxide) at least on the exposed surface of the islands. As anotherexample, a thin dielectric or organic film can be deposited directly asdiscontinuous and discrete islands. As another, third, example, a lowviscosity liquid or vapor with high surface contact angle can bedeposited. The surface tension will form discrete and discontinuousdroplets, for example, on non-magnetic spacer layer 33, 43, 53, 63,which are then heated to form solid non-conductive islands.

The magnetic elements of this disclosure (e.g., magnetic elements 30,40, 50, 60) may be made by well-known thin film building and removaltechniques such as chemical vapor deposition (CVD), physical vapordeposition (PVD), atomic layer deposition (ALD), spin coating,photolithography, dry etching, wet etching, or ion milling. The porousnon-conducting current confinement layer (e.g., current confinementlayer 38, 48, 58, 68) can be made by depositing material onto thenon-magnetic layer (e.g., non-magnetic spacer layer 33, 43, 53, 63). Forboth apertured material 70 and dotted material 80 that are suitable asporous non-conducting current confinement layer 38, 48, 58, 68, physicalpatterning (e.g., masking) is not necessarily needed to form the areasvoid of non-conducting material 72, 82.

FIG. 9A is a flow diagram of one possible process for making a magneticelement having a current confinement layer between the non-magneticlayer and the free layer, such as magnetic element 30, 40. Method 90Aincludes first forming a pinned layer at Step 91A, over which is applieda non-magnetic layer at Step 92A. A porous current confinement layer isformed over the non-magnetic layer in Step 93A, for example, eitherapplied as a previously formed layer or formed directly on thenon-magnetic layer. A free layer is formed over the current confinementlayer in Step 94A, filling the porous layer, as appropriate, with thefree layer material. It is understood that alternate processes formaking a magnetic element having a current confinement layer between thenon-magnetic layer and the free layer are possible.

FIG. 9B is a flow diagram of one possible process for making a magneticelement having a current confinement layer between the non-magneticlayer and the pinned layer, such as magnetic element 50, 60. Method 90Bincludes first forming a free layer at Step 91B, over which is applied anon-magnetic layer at Step 92B. A porous current confinement layer isformed over the non-magnetic layer in Step 93B, for example, eitherapplied as a previously formed layer or formed directly on thenon-magnetic layer. A pinned layer is formed over the currentconfinement layer in Step 94B, filling the porous layer, as appropriate,with the pinned layer material. It is understood that alternateprocesses for making a magnetic element having a current confinementlayer between the non-magnetic layer and the pinned layer are possible.

The magnetic elements of this disclosure (e.g., magnetic element 30, 40,50, 60 and variations thereof) can be utilized in a memory device. Aplurality of magnetic elements 30, 40, 05, 60 are arranged and connectedin an array with bit lines and word lines in a common way.

Thus, embodiments of the MAGNETIC MEMORY WITH POROUS NON-CONDUCTIVECURRENT CONFINEMENT LAYER are disclosed. The implementations describedabove and other implementations are within the scope of the followingclaims. One skilled in the art will appreciate that the presentdisclosure can be practiced with embodiments other than those disclosed.The disclosed embodiments are presented for purposes of illustration andnot limitation, and the present invention is limited only by the claimsthat follow.

1. A magnetic element comprising: a ferromagnetic pinned layer having apinned magnetization orientation, a ferromagnetic free layer having achangeable magnetization orientation, and a tunnel barrier layertherebetween; and a porous non-electrically conducting currentconfinement layer between the ferromagnetic free layer and theferromagnetic pinned layer, the porous non-electrically conductingcurrent confinement layer present between the ferromagnetic free layerand the tunnel barrier layer and providing an interface between theferromagnetic free layer and the tunnel barrier layer, or the porousnon-electrically conducting current confinement layer present betweenthe ferromagnetic pinned layer and the tunnel barrier layer andproviding an interface between the ferromagnetic pinned layer and thetunnel barrier layer, with the porous non-electrically conductingcurrent confinement layer having a thickness of 2 to 20 Angstroms. 2.The magnetic element of claim 1 wherein the porous non-electricallyconducting current confinement layer comprises a non-electricallyconducting material with a plurality of pores therein.
 3. The magneticelement of claim 2 wherein the plurality of pores have a diameter of 2to 200 Angstroms and are circular shaped.
 4. The magnetic element ofclaim 2 wherein the pores are orderly arranged.
 5. The magnetic elementof claim 1 wherein the porous non-electrically conducting currentconfinement layer comprises a plurality of islands of non-electricallyconducting material.
 6. The magnetic element of claim 5 wherein theplurality of islands have a diameter of 2 to 200 Angstroms and are domeshaped.
 7. The magnetic element of claim 5 wherein the islands arerandomly arranged.
 8. The magnetic element of claim 1 wherein the porousnon-electrically conducting current confinement layer comprises silica.9. The magnetic element of claim 1 wherein the porous non-electricallyconducting current confinement layer comprises a porous non-electricallyconducting material comprising an insulating or dielectric material. 10.The magnetic element of claim 1 wherein the porous non-electricallyconducting current confinement layer is present between theferromagnetic free layer and the tunnel barrier layer.
 11. The magneticelement of claim 1 wherein the pinned magnetization orientation and thechangeable magnetization orientation are both out-of-plane.
 12. Amagnetic element comprising: a ferromagnetic pinned layer having apinned magnetization orientation; a tunnel barrier layer; aferromagnetic free layer having a changeable magnetization orientation;a non-electrically conducting current confinement layer comprisingnon-electrically conducting material and areas devoid ofnon-electrically conducting material; a first interface between thetunnel barrier layer and the non-electrically conducting currentconfinement layer; a second interface either between thenon-electrically conducting current confinement layer and theferromagnetic free layer or between the non-electrically conductingcurrent confinement layer and the ferromagnetic pinned layer; and athird interface either between the tunnel barrier layer and theferromagnetic free layer or between the tunnel barrier layer and theferromagnetic pinned layer, present in areas devoid of non-electricallyconducting material.
 13. The magnetic element of claim 12 wherein thenon-electrically conducting current confinement layer has a thickness of2 to 20 Angstroms.
 14. The magnetic element of claim 12 wherein thesecond interface is between the non-electrically conducting currentconfinement layer and the ferromagnetic free layer, and the thirdinterface is between the tunnel barrier layer and the ferromagnetic freelayer.
 15. The magnetic element of claim 12 wherein the pinnedmagnetization orientation and the changeable magnetization orientationare both out-of-plane.
 16. A method of making a spin torque magneticelement having a current confinement layer, the method comprising:forming a ferromagnetic pinned layer and pinning a magnetic orientationof the ferromagnetic pinned layer; forming a tunnel barrier layer overthe ferromagnetic pinned layer; forming a porous non-electricallyconducting current confinement layer over and in contact with the tunnelbarrier layer; and forming a ferromagnetic free layer over the porousnon-electrically conducting current confinement layer.
 17. The method ofclaim 16 wherein forming a ferromagnetic free layer over the porousnon-electrically conducting current confinement layer comprises: fillinga set of pores in the porous non-electrically conducting currentconfinement layer with a ferromagnetic free layer material.
 18. Themethod of claim 16 wherein forming the porous non-electricallyconducting current confinement layer over and in contact with the tunnelbarrier layer comprises: depositing droplets of dielectric or organicmaterial over the non-magnetic spacer.
 19. The method of claim 16wherein forming the porous non-electrically conducting currentconfinement layer over and in contact with the tunnel barrier layercomprises: coating a porous film of dielectric or organic material overthe tunnel barrier layer.